The present disclosure is directed to a transport system or a transport arrangement especially for transporting piece goods as for example wafers or the like.
In the state of the art different transport systems are known, which use various systems or carrier systems to transport articles. The disclosure is described with respect to a machine for chemically polishing wafers. However, it is pointed out that the disclosure may also be used in other transport arrangements.
In the state of the art transport systems are known, which use for example permanent magnets and coils to produce a relative movement especially a movement in a linear direction. This principle has been applied since a long time for example in linear motors.
In one transport system known from the state of the art carriers are included which may be transported from two load positions to two process chambers. The transport system uses here a shared middle return track to transport the carriers back to the two load positions. This transport system consists of three horizontal linear motion systems (LMS-tracks). An upper and a lower track serve as a transport to the two process stations and the middle track as a return track as mentioned for the carriers. Furthermore, two vertical tracks, for example on the left and the right side of horizontal tracks are provided. These may be linear motor tracks with each two rotor or secondary parts which work as shuttles for the carrier. In all four shuttles a LMS-coil is mounted. This LMS-coil is moved by the shuttles and can therefore belong to two of the three LMS-coils.
In another machine known from the state of the art several LMS-tracks transport the carrier through the different process chambers in a for example counterclockwise direction. For this purpose several LMS-tracks are necessary. The carrier that is used covers multiple coils. This means that when the carrier is transported from one track to another, multiple coils are involved. To transport the carrier from for example a track 0 to a track 1 at least two coils of track 0 must be moved to the beginning of track 1. This also occurs between track 1 and 2 for example and other couples of tracks.
This movement of coils is however difficult to achieve. It is therefore one purpose of the disclosure to facilitate the movements and especially to facilitate the handling of movable coils.